1. Field of the Invention
The present invention relates to an optical coupler, and particular to a dynamic power optical splitter which integrates a dynamic FBG (Fiber Bragg Grating) and a circulator.
2. Description of Prior Art
Optical couplers are used in optical communication for coupling light from a number of input optical fibers into a number of output optical fibers. An optical splitter is a type of optical coupler wherein the number of output optical fibers is greater than the number of input optical fibers. The power of the input light is split into a plurality of predetermined portions and is output through the output optical fibers.
A conventional method of manufacturing an optical coupler is by fusing bare section of optical fibers together. Bare section of the fibers are placed in contact with each other and the section are heated and drown (placed under tension). This fuses the bare section of the fibers together.
Referring to FIG. 1, U.S. Pat. No. 5,988,892 discloses an optical splitter 3 which includes an input optical fiber 312 and two output optical fibers 314 and 316. A fused portion 318 is formed by heating and drawing the fibers 312, 314 and 316 during formation of the optical splitter 3. Mixed epoxy coverings 320 and 322 cover the interfaces between the fused portion 318 and the unfused portions of optical fibers 312, 314 and 316. The mixed epoxy coverings 320 and 322 are for improving the mechanical strength of the interfaces. Light input from the input optical fiber 312 passes through the fused portion 218 and divides into two beams which are output to the two output optical fibers 314 and 316.
A disadvantage of the above design is that the proportion of the power in the input fiber 312 output to each output fiber 314, 316 is fixed. A dynamic power optical splitter which can dynamically change the relative proportions of light output by the output optical fibers is desired.